1. Field of the Invention
This invention relates to an inverter generator, particularly to an inverter generator equipped with a generator unit driven by an internal combustion engine and adapted to remove harmonic distortion from the alternating current output to the utmost possible.
2. Description of the Related Art
One well-known inverter generator once converts the alternating current outputted by an engine-driven generator unit to direct current and then converts the direct current into alternating current of a predetermined frequency (utility frequency) by driving switching elements with a PWM signal generated using a reference sine wave of the desired output voltage waveform and a carrier (carrier wave). An example of such an inverter generator can be found in Japanese Laid-Open Patent Application No. H4 (1992)-355672 ('672).
In the prior art taught by this publication, the AC output voltage waveform is brought close to a sine wave by detecting the output voltage difference at the midpoint of four switching elements and correcting the reference sine wave in accordance therewith before supplying it to a pulse width modulation circuit for generating the PWM signal.